diff --git a/aiohttp/helpers.py b/aiohttp/helpers.py
index 861820599c3..5a74259eb3a 100644
--- a/aiohttp/helpers.py
+++ b/aiohttp/helpers.py
@@ -46,19 +46,7 @@ def __new__(cls, login, password='', encoding='latin1'):
     @classmethod
     def decode(cls, auth_header, encoding='latin1'):
         """Create a :class:`BasicAuth` object from an ``Authorization`` HTTP
-        header.
-
-        :param auth_header:  The value of the ``Authorization`` header.
-        :type auth_header:  str
-        :param encoding:  The character encoding used on the password.
-        :type encoding:  str
-
-        :returns:  The decoded authentication.
-        :rtype:  :class:`BasicAuth`
-
-        :raises ValueError:  if the headers are unable to be decoded.
-
-        """
+        header."""
         split = auth_header.strip().split(' ')
         if len(split) == 2:
             if split[0].strip().lower() != 'basic':
diff --git a/docs/client_reference.rst b/docs/client_reference.rst
index 69cea594ccf..c446a76d56d 100644
--- a/docs/client_reference.rst
+++ b/docs/client_reference.rst
@@ -1290,10 +1290,13 @@ BasicAuth
    e.g. *auth* parameter for :meth:`ClientSession.request`.
 
 
-   .. classmethod:: decode()
+   .. classmethod:: decode(auth_header, encoding='latin1')
 
       Decode HTTP basic authentication credentials.
 
+      :param str auth_header:  The ``Authorization`` header to decode.
+      :param str encoding: (optional) encoding ('latin1' by default)
+
       :return:  decoded authentication data, :class:`BasicAuth`.